Following reports of hundreds of dead fish floating in Bayou Rouge in Cottonport, Louisiana, the Louisiana Department of Wildlife and Fisheries (LDWF) conducted an investigation to find out what caused the fish kill.
Officials determined that that fish died from a low dissolved oxygen level in the water, basically suffocating the fish.
The low dissolved oxygen level was a result of multiple factors. Days before the fish kill, LDWF treated Bayou Rouge with a herbicide that targets specific plant life in the bayou and is deemed safe for aquatic animals. The decaying plant life at the bottom of the bayou from the herbicide, combined with the hot water temperatures, was stirred by the heavy rainfall. Those factors severely reduced the dissolved oxygen in the water, killing the fish.
“I do not know if there would have been a fish kill if we had not done the herbicide treatment,” said Daniel Hill, LDWF Biologist Manager Inland for Region Six. “It was very unfortunate timing.”